Two tech-related IPOs took off on Friday. Proto Labs (PRLB), a designer and maker of parts used mostly by electronics companies, priced late Thursday at $16 a share, above its proposed range of $13 to $15. The company sold 4.3 million shares, raising about $68.8 million. The stock started trading at 25 and was up near 28.70, up 79%, in early afternoon trading on Friday. Meanwhile, Bazaarvoice (BV), which uses social networking data to help